VirtualPathProvider on IIS 6 does not handle file stream caching correctly

Question

I am working on a framework where .aspx and .master pages are embedded in an assembly, using VirtualPathProvider to route a url to a specific embedded resource.

Sample url: /_framework.aspx/mypage.aspx (which uses /_framework.aspx/mymaster.master)

• _framework.aspx will make IIS6 route the request through ASP.NET framework
• everything after the .aspx is treated as a PathInfo in the .NET framework

In Visual Studio 2008 web server, the virtualPath is correctly: /_framework.aspx/mypage.aspx but in IIS6 the virtualPath is: /_framework.aspx

If I request two files: /_framework.aspx/file1.css and /_framework.aspx/file2.css the file2 will have the same content as file1.

I suspect that IIS6 considers the file path (_framework.aspx) and caches the file stream which is returned from the assembly, thus treating both urls as the same file.

Temporary solution:

I've implemented a CacheDependency class like this

class ImmediateExpiryCacheDependency : System.Web.Caching.CacheDependency
{
    public ImmediateExpiryCacheDependency()
    {
        base.NotifyDependencyChanged(null, null);
    }
}

It now expires the file stream cache, but doens't work with master pages, I guess because it is requested before the cache is expired through NotifyDependencyChanged.

Needed solution:

If I returned null in GetCacheDependency, IIS6 doesn't expire the file immediately. What is the correct way to immediately expire a file or disable the caching entirely. Even better, I would like to correct the way that IIS6 deals with the url, since the caching is actually good, if it would use the full file url.

Answer 1

Through my work in the ASP.NET Development Web Server, I had come to conclude that the correct FilePath would include the PathInfo, but I understand now that the IIS implementation is correct.

I changed my code so that ASP.NET files (aspx, ashx) would have a path such as /_framework/Default.aspx (since these files will be routed without special configuration) with a master page path such as /_framework/Site.master (since this is routed internally in the ASP.NET engine) and with image resources with a path /_framework.ashx/image.gif (since the .ashx will be routed to the ASP.NET engine, from where I will then use a kind of StaticFileHandler).

This way, all pages and resources can reside and remain entirely in the assembly :-)